Hypothenar

The hypothenar is the fleshy muscular eminence located on the ulnar side of the palm, opposite the thenar region. It is formed by a group of three intrinsic hand muscles—abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi—that originate from the flexor retinaculum and the hook of the hamate bone and insert onto the fifth digit. These muscles are innervated by the deep branch of the ulnar nerve, and they receive blood supply primarily from the ulnar and palmar arterial arches.

Functionally, the hypothenar muscles control movements of the little finger, including abduction, flexion, and opposition, contributing to grip strength and the ability to manipulate objects with the ulnar side of the hand. The opponens digiti minimi, in particular, draws the fifth digit toward the palm, allowing fine adjustments during precision tasks.

Clinical relevance of the hypothenar includes its role in ulnar neuropathy, where weakness or atrophy of these muscles may present as a flattened hypothenar eminence. The condition, often termed “hypothenar wasting,” can be observed in compression injuries at the wrist or prolonged pressure on the ulnar nerve. Additionally, hypothenar hammer syndrome, caused by repetitive trauma to the ulnar artery within the hypothenar region, can lead to vascular insufficiency and digital ischemia.

Variations in hypothenar muscle anatomy are reported, such as the presence of an additional muscle called the dorsoleus or variations in the size and attachment of the constituent muscles. These anatomical differences may influence hand mechanics and the presentation of neuropathic or vascular disorders.